img = imread("rainbow.jpg");
xs = [ .1 .2 .3 .4 ];
ys = [ .5 .3 .7 .4 ];
graphics_toolkit("fltk");
figure;
imshow(img);
hold on;
plot(xs*400, ys*400, 'b-o');
print -djpg "output_fltk.jpg";
graphics_toolkit("gnuplot");
figure;
imshow(img);
hold on;
plot(xs*400, ys*400, 'b-o');
print -djpg "output_gnuplot.jpg";